The present invention is concerned with the transportation of iron ore by pipeline. More particularly, the invention is concerned with the formation and pumping of aqueous slurries of iron ore containing additives to improve the viscosity characteristics of the slurries and to increase the carrying capacity of the slurry. In its more specific aspects, the invention is concerned with forming a pumpable aqueous slurry containing a range of particle sizes of iron ore, a dispersant such as lignosulfonate and an organic polymer.
Heretofore, many methods of pipelining aqueous slurries of granular material have been described and attempted. Many problems have been associated with pipelining granular material especially in the more dense materials such as iron ore and, in particular, hematite and magnetite. The world's first long distance iron ore slurry pipeline was put into service by Savage River Mines, Tasmania, Australia, on Oct. 26, 1967. Operation of this pipeline has been a technical success moving 2.2 million tons per year of iron ore a distance of 53 miles. The process used heretofore in pipelining iron ore comprised forming an aqueous slurry with finely ground iron ore without the use of additives. Thus, in operations heretofore, the iron ore has been ground so that it will pass a 325 mesh screen. In laboratory studies, it has been found that minus 325 mesh hematite will not flow in untreated slurries containing more than 28 percent hematite by volume. Thus the volumetric capacity of finely ground iron ore in slurry transportation methods is limited. In addition, it is very expensive to provide 100 percent finely ground ore. There has been no satisfactory solution as yet proposed which permits maximum pipeline transportation of a mix of sizes of iron ore particles which allows maximum volume transportation while preventing undesirable drop-out in the pipeline of the larger particles.